Microparticles have found wide use in delivering active ingredients, not only for use ex vivo, but, for delivering therapeutic agents or vaccines in vivo. Depending upon the size and chemical structure of the microparticle, pharmaceutical agents can now be specifically targeted such that the active ingredient is absorbed or otherwise taken up by the body in a manner that increases the effectiveness of drug or vaccine therapy.
As with all synthetic agents delivered to the body, microparticles themselves have undergone chemical processing or synthesis. A goal of the microparticle formulator is to prepare a biodegradable, biocompatible vehicle for delivery of active agents. Therefore, it is often desired that the microparticle only comprise those ingredients the formulator intends to deliver. Indeed, great care is taken to remove any unwanted substances that are present due to the processing conditions use to encapsulate the pharmaceutical agent.
One key impurity is the solvent that is used in microparticle formulation. The balance between efficiency of residual solvent removal and the cost of manufacturing a microparticle is significant to the industry. Typically large amounts of water are necessary during the extraction step in microparticle formation when the organic/water or water/organic/water emulsion is charged to an aqueous sink. The cost of water treatment, as well as the cost of water itself, becomes a cost factor for manufacturing microparticles on a production level.
There exists a need for a process for preparing microparticles resulting in low residual solvent levels while lowering the amount of water necessary to complete the process steps, and, therefore, the cost of manufacturing.